Treatment of certain diseases or conditions in patients can require frequent administration of medication or other fluid directly into the bloodstream of that patient. Frequent intravenous administration had previously been observed to cause or exacerbate complications. For example, repeated injection over a protracted period of time can cause damage to a blood vessel, e.g., collapse of a vein, which can render further or subsequent injection more difficult or painful.
Attempts to remedy such undesirable effects of frequent injection have come in the form of placement of a catheter into a blood vessel, e.g., a vein, wherein the catheter has a cannula portion which is placed inside the vessel and an injection port which remains outside the body and is accessible for frequent injection by a hypodermic needle and syringe or continuous drip or infusion pump. Although catheterization of the vessel can ameliorate damage to the vein, it does not completely eliminate the potential collapse or other damage to the vessel. Moreover, exposure of the injection port to the environment outside the skin can increase the susceptibility of contamination or infection at the wound site, or sepsis of the patient due to bacteria or other micro-organisms entering the site or blood stream via the catheter.
Recently, catheters have been developed which have a cannula portion which inserts into the blood vessel and an injection port for delivery of medication and fluids wherein the entire cannula and injection port are placed completely under the skin. These are well known in the art as "implantable access systems" and are commercially available, for example, as PORT-A-CATH and P.A.S. PORT systems (SIMS Deltex, Inc., St. Paul, Minn.). These systems are described in one or more of the U.S. Pat. Nos. 4,887,414 and 4,963,133 which are hereby incorporated by reference.
The PORT-A-CATH system is placed under the skin with the catheter inserted into a vein in the chest. The tip of the catheter is inserted into a vein and the delivery tip positioned at a point just above the heart. The injection port can be placed at a convenient place under the skin, e.g., above the pectoral muscle. The P.A.S. PORT system is typically placed under the skin with the catheter placed into a vein in the lower arm. The tip of the catheter is located in a vein at a point just above the heart, similar to that PORT-A-CATH system. The access port of the P.A.S. PORT system is positioned under the skin and above a muscle in the forearm.
To access either system, a specially designed non-coring needle can be inserted through the skin directly into an access port comprising a septum. The access port in an implantable access system comprises a small metal chamber which is sealed at the top by a septum made of self-sealing silicone. The housing of the port can be made from medical-quality metal, e.g. titanium, or other medically acceptable rigid material. The cannula or catheter portion can be a thin flexible tube made from silicone or polyurethane. These materials are known for their long, useful life when placed inside the human body.
Although these implantable access systems can reduce the risk of infection, the systems are not without certain disadvantages. For example, care of the system can require frequent flushing with an anticoagulant, e.g., heparin solution to prevent blood clotting, especially after injection or infusion when blood may enter the system during administration of a medication. In addition, during an infusion, a needle or catheter is continuously in place during treatment and requires that a dressing be used to cover the needle or catheter injection site. The dressing secures the catheter in position and helps to keep the injection site clean.
One example of a stabilization dressing is Veni-Gard.RTM. (Con-Med Patient Care Systems, Utica, N.Y.). The Veni-Gard stabilization dressing comprises a sterile, transparent polymeric sheet having an adhesive disposed on one face which contacts the skin and catheter in order to stabilize the catheter, and a cushioned adhesive strip affixed around its periphery to secure the dressing in place. These, and other dressings indicated for use on surgical sites, e.g., Tegaderm (3M Corneal epithelial erosion., Minneapolis, Minn., USA) and OpSite Flexgrid (Smith & Nephew, Hull, England), can be disadvantageous in that the adhesive can stick to the catheter insertion site, to the incision, or to any tape, stitches, or staples used to close the incision. The medical professional applying the dressing must therefore "wet" the site prior to application of the dressing to prevent adherence at any undesired site or to any component of the catheter system.
Moreover, these stabilization or surgical dressings are not completely waterproof, and typically would not allow the user to bathe or shower without getting the site wet, risking contamination or infection of the site. These dressings are not indicated as a waterproof seal for use during bathing or showering, and have not been suggested for such use or for implantable access systems. Keeping the dressing dry can thus hamper the patient's ability to bathe or shower in a normal fashion.
Although medical professionals have, in the past, recommended covering the dressing with a plastic bag or other waterproof or water resistant sheet material taped over the dressing during bathing, there has heretofore been no such article available that can successfully keep water from the area intended to be kept dry. Patients have found that taping a plastic bag or other waterproof or water-resistant sheet material over the dressing is only minimally successful. Water from the bath or shower can often leak or seep into the area to predispose the injection site to contamination or infection.
Thus, there is a need for providing a means for keeping an area on the body dry during bathing or showering, wherein the body area is a surgical site, catheterization site, or injection port site. Such an article or method for use with an implantable access system would be highly desired and advantageous.